This article provides a complete guide to the use of VBA dictionaries.
In VBA we can use Arrays and Collections to store groups of values. For example, we could use them to store a list of customer names, student marks or a list of values from a range of cells. A Dictionary is similar to a Collection.
The Collection, however, has two major faults: We cannot check if the key already exists, and we cannot change the value of an existing item. The VBA Dictionary does not have these issues. You can check if a Key exists and you can change the Item. This makes the Dictionary a very useful and versatile data structure.